1. Field of the Invention
The present invention relates to telecommunications and, more particularly, to a “virtual” visitor location register for a wireless local area network.
2. Description of Related Art
A traditional enterprise telephone network includes a number of landline extension telephones (either analog or digital) connected to a private branch exchange (PBX). The PBX, in turn, is connected to the public switched telephone network (PSTN), e.g., via a primary rate interface or a basic rate interface. Increasingly, however, more diverse types of communication devices are being used in enterprise networks. For example, the PBX may be connected via a local area network (LAN) to packet-based communication devices, such as voice-over-packet (VoP) telephones or audio-equipped personal computers. In addition, the PBX may be an “IP-PBX” communicatively coupled to a packet-switched network, such as the Internet, instead of or in addition to the PSTN.
The PBX may also be part of a wireless local area network (WLAN) that includes one or more wireless access points for communicating with mobile stations over air interfaces. Such mobile stations may include wireless telephones, wirelessly-equipped personal digital assistants (PDAs), wirelessly-equipped laptop computers, and/or other wireless communication devices. The air interface communications may conform to a WLAN specification, such as IEEE 802.11b, Bluetooth, HomeRF, or HiperLAN. Alternatively, or additionally, the air interface communication may occur in a cordless telephone format, in a Multichannel Multipoint Distribution Service (MMDS) format, or in some other format. Some of these mobile stations may also be able to communicate with a wireless wide area network (WWAN), using an air interface format such as CDMA or GSM. Thus, when a multi-mode mobile station is within the wireless coverage area of the WLAN, it may use the WLAN for communication, and when the multi-mode mobile station is within the wireless coverage of the WWAN, it may use the WWAN for communication.
WWAN signaling protocols, such as IS-41, typically support roaming between areas served by different serving systems. For example, each serving system in a WWAN may include a visitor location register (VLR) that communicates with a home location register (HLR) for mobility management and other purposes. Now, with the interest in multi-mode mobile stations that may be in communication with either a WWAN or a WLAN at any given time, there is a need to provide additional systems and methods for mobility management in order to facilitate roaming between the WWAN and WLAN. For example, it is desirable to be able to reach a multi-mode mobile station by dialing the same directory number, regardless of whether the multi-mode mobile station is in communication with the WWAN or with the WLAN.